Senna primarily acts as what type of laxative?

• A. Osmotic laxative
• B. Bulk-forming laxative
• C. Lubricant laxative
• D. Stimulant laxative

Answer: (D)

Senna acts primarily as a stimulant laxative. Its active compounds irritate the lining of the colon and stimulate the enteric nerves, increasing peristaltic contractions and speeding stool movement. This motility-stimulating effect explains why senna typically produces a bowel movement within a few hours after oral dosing. This mechanism differs from osmotic laxatives that pull water into the bowel, bulk-forming laxatives that swell to trigger stretch and movement, or lubricant laxatives that coat stool to ease passage.